Comment by sansseriff

Comment by sansseriff 2 days ago

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Cameras capture linear brightness data, proportional to the number of photons that hit each pixel. Human eyes (film cameras too) basically process the logarithm of brightness data. So one of the first things a digital camera can do to throw out a bunch of unneeded data is to take the log of the linear values it records, and save that to disk. You lose a bunch of fine gradations of lightness in the brightest parts of the image. But humans can't tell.

Gamma encoding, which has been around since the earliest CRTs was a very basic solution to this fact. Nowadays it's silly for any high-dynamic image recording format to not encode data in a log format. Because it's so much more representative of human vision.

ttoinou 2 days ago

Ok so similar to the other commentator then, thanks. According to that metric its much more than 90% we’re throwing out then (:

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  • lucyjojo 2 days ago

    well technically there's a bunch of stuff that happens after the sensor gets raw data. (also excluding the fact that normal sensors do not capture light phase)

    demosaicing is a first point of loss of data (there is a tiling of monochrome small sensors, you reconstruct color from little bunches with various algorithms)

    there is also a mapping to a color space of your choosing (probably mentioned in the op video, i apologize for i have not watched yet...). sensor color space do not need to match that rendered color space...

    note of interest being that sensors actually capture some infrared light (modulo physical filters to remove that). so yeah if you count that as color, it gets removed. (infrared photography is super cool!)

    then there is denoising/sharpening etc. that mess with your image.

    there might be more stuff i am not aware of too. i have very limited knowledge of the domain...

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    • ttoinou 2 days ago

      But even before sensor data we go from 100 bits of photons data to 42 bits counted by photosites. Mh well maybe my calculations are too rough

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  • strogonoff a day ago

    The amount of captured sensor data thrown out when editing heavily depends on the scene and shooting settings, but as I wrote it is probably almost always 90%+ even with the worst cameras and widest possible dynamic range display technology available today.

    In a typical scene shot with existing light outdoors it is probably 98%+.

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